In recent years, in the 3rd Generation Partnership Project (3GPP) that is the standards organization related to radio communication systems, studies have been conducted on the fifth generation mobile communication system (5G). In the fifth generation mobile communication systems, services conforming to eMBB (enhanced mobile broadband), mMTC (massive machine type communications), URLLC (Ultra Reliability and Low Latency Communications), and the like are going to be started.
For example, eMBB responds to a service of transmission of large-volume data, such as moving image data. In contrast, URLLC responds to a service in which high-reliable and low-latency communication is needed, such as automatic operations or telesurgery. In order to implement these services, discussions are actively conducted on how to set communication parameters, such as Transmission Time Interval (TTI), that is the duration of time represented by, for example, flames or subframes.
Specifically, for example, when eMBB data and URLLC data are transmitted by using the same frequency band, it is conceivable to multiplex the eMBB data and the URLLC data by using time-division multiplexing or frequency-division multiplexing. At this time, because a low latency is needed for the URLLC data, a large reduction in TTI of URLLC compared to TTI of eMBB is studied.    Non-Patent Document 1: LG Electronics, “Handling URLLC in new RAT”, 3GPP TSG RAN WG1 Meeting #86, R1-166886, August 2016    Non-Patent Document 2: NTT DOCOMO, INC., “On co-existence of eMBB and URLLC”, 3GPP TSG RAN WG1 Meeting #86, R1-167391, August 2016    Non-Patent Document 3: Samsung, “Discussion on URLLC support in NR”, 3GPP TSG RAN WG1 Meeting #86, R1-166759, August 2016
However, when eMBB data and URLLC data are multiplexed in the same frequency band, there is a problem in that the efficiency of using time and frequency resources is reduced. Specifically, because URLLC data is transmitted to control, for example, automatic operations, URLLC data to be transmitted is not always present and, accordingly, intermittent transmission occurs in URLLC data. Nevertheless, if time and frequency resources are fixedly allocated to URLLC data, the resources allocated to the URLLC data are wasted when URLLC data to be transmitted is not present.